Earth and Space Sciences: Star Life Cycles

Hubble’s Law

The farther away a galaxy is, the faster it is moving (expansion is evidence for a beginning)

nuclear fusion

H fuses into He and so on

E=mc^2

Einstein’s equation that describes the energy resulting from a small amount of mass lost during fusion.

The sun is made of several layers, including the ____, ____________, _________, __________, _________, and ______

the core, radiative zone, convective zone, photosphere, chromosphere, and corona

A star’s size is primarily a balance between the outward force of _____ and the inward force of _______.

fusion and gravity

What kind of star would support an Earth-like planet?

A Sun-like start (in mass) which is stable and at or close to equilibrium.

What should we consider about stars if we want to determine how long their life spans are?

By the amount of hydrogen and helium, hydrogen is their fuel.

The Sun has provided Earth with energy for ______ years and it is expected to do so for another ______ years.

5 billion, 5 billion

luminosity

rate of energy released

Why do new stars form out of hydrogen gas and a dust cloud?

Hydrogen is the fuel for a star’s life, so the make up of the stars has to be mostly hydrogen.

Why do stars change very little while they are in the Main Sequence stage?

How do Main Sequence stars change quickly when they grow into a Red Giant?

Depending on a star initial mass, the last stage of a star life cycle is either a white dwarf, neutron star or a black hole. Why are these some of the most dense objects in the universe?

Why do more massive stars die faster than less massive stars?

How does the rate of star death relate to the luminosity of a star (amount of energy released per second)?

What factors lead to a star’s stability or instability? Why is it important to understand how long a star is stable and when might it change?

What is the role of gravity?

Gravity pulls elements closer to each other.

The more gravity, the ______ elements can fuse with each other.

faster